Oracle-L: RE: Prevent FTS

From: <manoj.gurnani_at_orbitech.co.in>
Date: Mon, 06 Jan 2003 10:30:31 -0800
Message-ID: <F001.00527C84.20030106103031@fatcity.com>

col_1 and col_2 are primary key columns in all 3 tables. There is no implicit data type conversion. col_1 is varchar2 and col_2 is varchar2 in all 3 tables. col width is also same in all 3 tables.

-----Original Message-----
Sent: Monday, January 06, 2003 11:52 PM
To: Gurnani, Manoj

If an implicit data type conversion occurs within the WHERE clause, a Full Table Scan will always results.
It is equivalent to placing a function on an index.

Are all the columns involved indexed?

Forwarded by Charlie Mengler/THD on 01/06/2003 10:15 AM -----

                      manoj.gurnani_at_orb                                         
                                                
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                      root_at_fatcity.com         Subject:  Prevent FTS            
                                                
                                                                                
                                                
                                                                                
                                                
                      01/06/2003 09:39                                          
                                                
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Hi All,
          I've  3 tables   table x,y,z

pk of x is (col_1,col_2),pk of y is (col_1,col_2,col_4,col_5),pk of z is
(col_1,col_2)

where clause is :

where x.col_1 = y.col_1

and x.col_2 = y.col_2
and x.col_1 = z.col_1
and x.col_2 = z.col_2
and y.col_1 = z.col_1
and y.col_2 = z.col_2

and x.col_3 in ('val1','val2','val3')
and.....
..

Explain plan shows that there is a FTS of table z . what can be the reason for this and how to prevent this.

Thanks
Manoj

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Please see the official ORACLE-L FAQ: http://www.orafaq.net
-- 
Author: 
  INET: manoj.gurnani_at_orbitech.co.in

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Received on Mon Jan 06 2003 - 12:30:31 CST